J/MNRAS/369/723 Fourier parameters for Cepheid variables (Ngeow+, 2006)
Period-colour and amplitude-colour relations in classical Cepheid variables.
IV: The multi-phase relations
Ngeow C., Kanbur S.M
<Mon. Not. R. Astron. Soc. 369, 723 (2006)>
=2006MNRAS.369..723N 2006MNRAS.369..723N
ADC_Keywords: Stars, variable ; Photometry
Keywords: Cepheids - stars: fundamental parameters
Abstract:
The superb phase resolution and quality of the OGLE data on LMC and
SMC Cepheids, together with existing data on Galactic Cepheids, are
combined to study the period-colour (PC) and amplitude-colour (AC)
relations as a function of pulsation phase. Our results confirm
earlier work that the LMC PC relation (at mean light) is more
consistent with two lines of differing slopes, separated at a period
of 10 days. However, our multi-phase PC relations reveal much new
structure which can potentially increase our understanding of Cepheid
variables. These multi-phase PC relations provide insight into why the
Galactic PC relation is linear but the LMC PC relation is non-linear.
This is because the LMC PC relation is shallower for short (logP<1)
and steeper for long (logP>1) period Cepheids than the corresponding
Galactic PC relation. Both of the short and long period Cepheids in
all three galaxies exhibit the steepest and shallowest slopes at
phases around 0.75-0.85, respectively. A consequence is that the PC
relation at phase ∼0.8 is highly non-linear. Further, the Galactic and
LMC Cepheids with logP>1 display a flat slope in the PC plane at
phases close to the maximum light. When the LMC period- luminosity
(PL) relation is studied as a function of phase, we confirm that it
changes with the PC relation. The LMC PL relation in V- and I-band
near the phase of 0.8 provides compelling evidence that this relation
is also consistent with two lines of differing slopes joined at a
period close to 10 days.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 125 154 V-band Fourier parameters for the Galactic Cepheid
tablea2.dat 125 154 I-band Fourier parameters for the Galactic Cepheid
tablea3.dat 208 641 V-band Fourier parameters for the LMC Cepheid
tablea4.dat 209 641 I-band Fourier parameters for the LMC Cepheid
tablea5.dat 125 390 V-band Fourier parameters for the SMC Cepheid
tablea6.dat 125 390 I-band Fourier parameters for the SMC Cepheid
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See also:
J/AcA/49/543 : OGLE LMC + SMC Cepheids VI photometry (Pietrzynski+, 1999)
J/AcA/49/437 : BVI photometry of OGLE SMC Cepheids (Udalski+, 1999)
J/AcA/49/223 : BVI photometry of OGLE LMC Cepheids (Udalski+, 1999)
Byte-by-byte Description of file: tablea?.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Name Cepheid identification (1)
17- 21 F5.3 mag E(B-V) Extinction value
23- 30 F8.6 [d] log(P) Log period
32- 37 F6.3 mag A0 V or I band mean magnitude
39- 44 F6.4 mag A1 Fourier amplitude A1
46- 51 F6.4 rad phi1 Fourier phase phi1
53- 58 F6.4 mag A2 Fourier amplitude A2
60- 65 F6.4 rad phi2 Fourier phase phi2
71- 76 F6.4 mag A3 Fourier amplitude A3
78- 83 F6.4 rad phi3 Fourier phase phi3
85- 90 F6.4 mag A4 ? Fourier amplitude A4
92- 97 F6.4 rad phi4 ? Fourier phase phi4
99-104 F6.4 mag A5 ? Fourier amplitude A5
106-111 F6.4 rad phi5 ? Fourier phase phi5
113-118 F6.4 mag A6 ? Fourier amplitude A6
120-125 F6.4 rad phi6 ? Fourier phase phi6
127-132 F6.4 mag A7 ? Fourier amplitude A7
134-139 F6.4 rad phi7 ? Fourier phase phi7
141-146 F6.4 mag A8 ? Fourier amplitude A8
148-153 F6.4 rad phi8 ? Fourier phase phi8
155-160 F6.4 mag A9 ? Fourier amplitude A9
162-167 F6.4 rad phi9 ? Fourier phase phi9
169-174 F6.4 mag A10 ? Fourier amplitude A10
176-181 F6.4 rad phi10 ? Fourier phase phi10
183-188 F6.4 mag A11 ? Fourier amplitude A11
190-195 F6.4 rad phi11 ? Fourier phase phi11
197-202 F6.4 mag A12 ? Fourier amplitude A12
204-209 F6.4 rad phi12 ? Fourier phase phi12
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Note (1): Variable name for Galactic Cepheids (tables A1 and A2),
OGLE (Udalski et al., 1999, Cat. J/AcA/49/437) name for
SMC Cepheids (tables A3 and A4),
OGLE (Udalski et al., 1999, Cat. J/AcA/49/223) or
HV (Hodge & Wright, 1967SAOP.4699....1H 1967SAOP.4699....1H) name for LMC Cephedis
(tables A5 and A6)
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Acknowledgements: Chow-Choong Ngeow, cngeow(at)astro.uiuc.edu
(End) Patricia Vannier [CDS] 19-May-2006